The astronomical length of DNA
Just how long is all of your DNA?
Let’s start with a quick recap. The sequence of Deoxyribonucleic acid (DNA), is famously spelt out in just 4 letters — A T G and C. Each letter represent the repeating ‘bases’; adenine, thymine, guanine and cytosine. And the famous DNA double helix is a twisted ladder, each rung made from a pair of bases. Adenine always pairs with thymine whilst cytosine pairs with guanine.
So the first thing we need to know is the distance between each rung on that DNA helical ladder. And that’s easy. Watson, Crick, Franklin and Gosling worked that out for us, and its 0.34 nanometers.
There are just over 3 billion base pairs in the Human genome, a copy of which is in (almost) all your cells. So that works out at a nice tidy 1 meter of DNA per cell (or there about). Which is pretty amazing it itself, all that DNA packed away inside something about 50μm long.
The Human body contains an estimated 37 trillion cells. Which means there’s 37 billion kilometers of DNA tucked away within you. That’s enough to stretch from the Sun to Neptune and back … 4 times!
